Cleanable sieve



Oct. 27, 1936. R. NEHER CLEANABLE SIEv IE .Filed Sept. 11, 1951 Patented Oct. 27, 1936 UNITED STATES PATENT OFFICE National Gypsum Company, corporation of Delaware Application September 11, 1931, Serial No. 562.278

11 Claims. (01- 209-379) This invention relates to a sieve, i. e., a screen or foraminous plate for holding back or screening out relatively coarse particles of material, and more particularly to a sieve for use in the bottom of a wet gypsum-aggregate mixer whereby to prevent the extrusion of any excessively large and non-uniformly mixed lumps from said mixer.

The principal object of the invention is to provide a sieve which may be conveniently cleaned or cleared out whenever the same becomes excessively clogged up, without the necessity of stopping the entire machine for this periodic cleaning process. Numerous other collateral objects of the invention are disclosed in detail in the herein patent specification wherein:

In the accompanying drawing:

Fig. 1 is a fragmentary top plan view, with the cover removed, of a gypsum-aggregate mixer with my improved cleanable sieve arranged in the bottom thereof.

Fig. 2 is a vertical transverse section thereof taken on line 2-2, Fig. 1.

, Fig. 3 is an enlarged, fragmentary section thereof taken on line 3-3, Fig. 1, but with the imperforat'e plate in its closed position.

Similar characters of reference indicate like parts in the several figures of the drawing.

The present invention is illustrated as used in combination with and as a part of a toothed ballmiil mixer employed for mixing gypsum with aggregate in a moist condition. A typical form of such a mixer is illustrated, the same comprising a casing in having vertically cylindrical side walls ii, an approximately flat bottom or floor l2, a cover H, a vertical, coaxial agitator shaft l4, and a hollow or tubular scraper shaft IS. The lower end of said agitator, shaft I4 is suitably journaled in the mixer floor l2 by means of a vertical thrust ball bearing l6 and a radial ball bearing l1. The upper end of said agitator shaft is connected to and driven by any suitable source of power, while to the lower end above the radial ball bearing i 'l) is secured, by a key l8, an agitator wheel 20. The periphery of this agitator wheel is serrated to provide a plurality of agitator teeth 2i which are circumferentially uniformly spaced around the periphery of said agitator wheel 20. Each of these agitator teeth 2| is bevelled at 22 and is curvilinear or arcuate in shape and terminates abruptly at its rear end in a square-shouldered, radial indenture 23, at the innermost end of which is located the leading end of the next successive curvilinear agitator tooth 2|.

A plurality of mixing spheres or balls 24 are disposed around the inner periphery of the cylindrical side wall of the mixer, these balls being caused to roll around the inner periphery of the stationary cylindrical side wall I I and at the same time caused to jump up and down by means of the rotation of said agitator wheel 20 and its peripheral, curvilinear teeth 2|. A ball-race wear plate 25 is customarily sunk or imbedded in the inner periphery of the cylindrical side wall ll of the mixer casing l so as to enable the same to be replaced, without replacing the entire side wall ii, when the mixer has been in use a considerable period and has become excessively worn down.

Such a mixer is preferably and usually also provided with a scraper hub 26 which is secured (by a press fit) to and is driven by the tubular scraper shaft IS, the speed of the latter being different from the rotative speed of the agitator shaft I4. Secured to said scraper hub 26 by machine screws 21 or otherwise is an upper or cover scraper blade 28, to the outer end of which is fastened, by rivets 30, a vertical or wall scraper 3|. Also secured to said scraper hub 26, by screws 210 or otherwise, is a lower scraper blade 22, the'lower edge of which slidingly engages with and thereby scrapes off the upper surface of the agitator wheel 20. The vertical load thrust or weight of all of these various scraper blades, together with the scraper hub 26 and tubular scraper shaft I is borne by a suitable scraper, thrust-bearing 33, while the lateral (horizontal) thrust is borne by a pair of anti-friction bushings 34. 7

It is to be understood that, although this toothed ball-mill mixer has been described in detail, it forms no organic part of the present inventicn and has only been thus described so as to make the present disclosure entirely intelligible. The essence of the herein invention is concerned only with the sieves which are located at the bottom of said mixer and are constructed as follows:

At the discharge side of the mixer (lower part of Fig. 1) the floor or bottom plate I2 is arcuately cut away at three points 35 and into each of the cut-away portions is secured, by machine screws 26 or otherwise, a flanged, semi-circular, sieve collar 31. Projecting coaxially upwardly from the outer central part of each sieve collar is a post or vertical pivot 38, secured in place by a set screw 40 or otherwise. Rotatably mounted on each of said pivots 38 is a pair of plates, namely:

'a sieve plate II and an imperforate plate 42, both of said plates being disposed horizontally and having their adjacent faces in close juxtaposition, the imperforate plate 42 being illustrated as being uppermost. Each sieve plate 4| is provided with a plurality of arcuate slots or semicircular sieve openings 42 which are concentric with respect to the companion pivot 22 and are radially equally spaced from each other. Press fitted or otherwise secured to the bottom face of each imperforate plate 42 are aplurality of clearing prongs 44 the lower ends of which are bevelled at 45. Each of said clearing prongs projects downwardly into and is snugly received. within a companion arcuate opening 42 of its companion sieve plate 4|. Each sieve plate is provided with a radial, outwardly projecting, op-

erating handle 42, while each-imperforateplate,

42 is similarly provided with an operating handle 41. The annular (semi-circular) edge of each imperforate plate 42 is provided with a singlebevelled periphery 42 which is received in and is guided by a single bevelled guideway' Informed coaxially with respect to the pivot 28, in its companion sieve collar 21. The annularisemi-circular) edge of each sieve plate 4l', on .the other hand, is provided with a double-bevelled periphery 5| which is received in and is guided by a double-bevelled guideway 52 formed (also coaxially with the pivot 22) in its companion sieve collar 21.

Operation The gypsum and viscous aggregate (or other materials to be intimately ground together and mixed) are fed into the top of the cylindrical casing I 0 and are thoroughly mixed therein by.

the combined rolling and up and down jostling action oi the mixing balls 24, the same being caused to rotate by reason of the rotationof the agitator wheel 20 driven by the agitator shaft 4, and being caused to be jumped up and down by reason of the agitator teeth. 2| of said agitator wheel. The material being mixed is prevented from permanently sticking to the inner parts of the mixer by reason of the various scraper blades 28, 2| and 22 driven by the tubular scraper shaft II.

Normally, while the mixer is in operation, the mixed material is squeezed by gravity and by the action of the balls 24 down through the bore of the three sieve collars 21 and throughthe arcuate sieve openings 42 of the sieve plate 4|. These sieve plates hold back or retain the excessively large lumps of material and the insufficiently mixed accretions, thereby ensuring that only.

sufliclently fine and masticated or mixed material will be discharged from the mixer. I

It occasionally happens, however, that the sieve openings 42 of said sieve plates become clogged up and it has heretofore been the practice to shut down the entire machine in order to eiIect a cleaning or clearing out of said sieve plate openings. In the present invention, the operator does not need to disturb the operation of the machine. Instead he merely grasps the operating handle 46 of the more or less clogged-up sieve plate and rotates the same a half revolution in a clockwise direction. This action causes the clearing prongs of the companion imperforate plate 42 to traverse the arcuate openings 42 of the oifending sieve plate 4| .and to push out therefrom any clogged up material; The bevelled end 45 of each clearing prong'45 permits the latter to only touch the one (outer) side of its sieve opening 42 with its entire length, the other (inner) side of said sieve opening being only partly engaged by its companion cleaning prong 45. This construction prevents anywedglngbr or more of the sieve plates 4|. In the present invention, such a result is obtained by merely grasping the operating handle 41 of the desired imperforate plate 42 and turning the same in a -counter-clockwise direction as far as may be desired, thus cutting off any desired amount of the flow through its companion sieve plate 4|.

It should be noticed that, each imperforate 1 plate 42 is. located above its companion sieve -plate 4|, so that the portions of the arcuate sieve openings 42 which are not in use are covered, as otherwise they would be likely to become packed .hard with the material being macerated in the mixer and would require being cleaned out before being fit for service when the imperforate plate is subsequently to be more or less opened up. The effect of the bevelled peripheries of each sieve plate 4| and imperforate plate 42 are also of importance. The double-bevelled periphery 2| of each sieve plate 4|, engaging as it does with the double-bevelled guideway 52 of the sieve collar 21, restrains said sieve plate against upward as well as downward displacement, and thus relieves the vertical strains which would otherwise be imposed on the pivot 22 and at the same time definitely restrains said sieve plate against any accidental upward displacement and against excessive upward pressure against the imperforate plate 42. The latter, having its semi-circular edge formed to provide the single bevelled periphery 42 (which is received by the single-bevelled guideway ensures that the lower face of said imperforate plate is always in close contact with the upper face of the sieve plate 4| this ac tion being ensured by the fact that inevitably, a certain amount of to-be-mixed material is sure to be packed in between said single bevelled pe-, riphery 48 and its companion single bevelled guideway Ill. v

I claim as my invention: 1. A sieve adapted to screen material and comprising a pivoted arcuate plate provided with a concentric, arcuate opening through which the entire mass of said material is adapted to flow; a clearing prong normally located at one end of said opening and projecting thereinto; and means whereby said plate may be swung about its pivot in a plane perpendicular to said clearing prong and thereby to clear said opening. 1

2. A sieve adapted to screen material and comprising a normally stationary pivoted arcuate plate provided with a concentric, arcuate opening through which the entire mass of said material is adapted to flow; a clearing prong normally located at one end of said opening and projecting thereinto; and means whereby said plate may be swung about its pivot in a plane perpendicular to said clearing prong and thereby to clear said opening.

1 3. A sieve adapted to screen material and comprising a pivot; a sieve plate having an arcuate opening through which the entire mass of said material is adapted to flow arranged concentrically with respect to said pivot; and an imperforate plate adapted to swing about'said pivot and 4 saidmaterial is adapted to a plate and having projecting into '1. A sieve adapted to screen material and arsaid pivot .parallel with the axis of said provided-with aclearing prong arranged parallel with the axis of said sieve plate and projecting 1 l a concentrically arranged opening through which the entiremass of said material is adapted to flow; and an imperforate plate also arranged on and also adapted'to be moved about saidpivot and'having projecting into said opening.

, v 5. .A sieve adapted to screen material and comprising a pivot; a sieve opening through which plate having an arcuate pivot and provided with a handle whereby it may be manually swung about saldpivot; an.

imperforate plate also mounted on said pivot and also provided with a handle whereby itmay be manually swung about plate and secured to said imperforate, plate and projecting into the arcuate-opening of said sieve plate V v t 6. A sieve comprising a sieve plate'adapted to screen material by restraining the flow. there-1 through of excessively large particles and havingo perforate-plateadapted to have'its leading edge an opening through which the entire mass of plate arrangedagainst one flat face. of-said sieve a bevelled periphery; a casing having a bevelled guideway which receives the peripheral edge of said sieveplate; and a clearing prong secured to said imperforate plate and the'opening of saidsieve plate.

- ranged'in a casing having a pair of oppositely plate also having a bevelled guideways; a sieve plate having an opening through which the entire mass of said material is. adapted to flow and having a bevelled edge arranged to engage with one of the bevelledguideways of said casing; and an imperforate bevelled edge and arranged to engage with the other bevelled a clearing prong arranged sieve plate and the entire mass of saidmaterial is adapted toflow and mounted on said said pivot; and a clearing prong arranged parallel with the axis of said sieve flow; an imperforateguideway of saidcasing; anda clearingprong secured to said J imperforate plate and projecting into the opening of said sieve plate. I

8. In a sieve for a gypsum-aggregate mixer and adapted to restrain the flow therethrough of the coarse and improperly mixed lumps, comprising a casing having a singleannular bevelled guideway and a double annular bevelled guideway; a pivot arranged in said casing; ing a double bevelled periphery and arranged to an imperforate plate having a single bevelled periphery and arranged to engage with said opening of said sieve plate;

- 9. A cleanable sieve comprising: a frame; a. sieve plate having anelongated opening; an imperforate plate adapted to have its leading edge moved horizontally over the upper surface of said slave plate; and a clearance prong projecting within said opening. a

10. A cleanable sieve comprising:a frame; a

sieve plate having an elongated opening; an immoved horizontally. over and in intimate shearing contact with the upper surface of said sieve l-plate;t. and a clearance prong projecting downwardlyfromtheloweriace of said imperforate plate back of its leading edge and received within said opening. A 1

' 11. A cleanable sieve comprising: a frame; a sieve plate having an elongatedopening: an imperforate plate having a leading edge and adapted to cover the entire surface of said sieve plate and to .be moved over the upper surface thereof; and a clearance prong located just back of the leading edge of said imperiorate plate and pro-- jecting' downwardly from the lower face thereof and received withinsaid opening.

ROYNEHER.

a sieve plate havdownwardly from the lower face oi said imper-' forate plate back of its leading edge and received engage with said double bevelled guideway and havingan arcuate opening through which the entire mass of said materialis adapted to flow; 

